MEXICO CITY - Mexico's flu outbreak appeared to be stabilizing on Saturday but officials warned it was too early to ease vigilance against an unpredictable virus which still threatens a global pandemic.

It would still be imprudent to say that we're past the worst of it but I do think...we are in a stage of stabilization, Mexican Health Minister Jose Angel Cordova told reporters.

In Geneva, a World Health Organization official said the virus had not spread in a sustained way outside North America, as would be required before the global pandemic alert level is raised to its highest level -- but he added he still expected this to happen.

I would still propose that a pandemic is imminent because we are seeing the disease spread, Michael Ryan, WHO Director of Global Alert and Response, told a briefing.

Few are ready to take chances with the new A-H1N1 virus, widely dubbed swine flu. In Hong Kong, police quarantined a hotel after a Mexican guest fell ill with the virus, which has spread to at least 16 countries around the world and may have killed more than 100 people in Mexico, the worst hit.

Mexican authorities cut their suspected death toll to up to 101 from as many as 176 as more test samples came back negative. Fewer patients with severe flu symptoms were checking into hospitals, suggesting a falling infection rate, and no new deaths were reported in Mexico City in the last two days.

The World Health Organization said on Saturday 15 countries have reported 615 infections. In addition, Italy has reported one confirmed case.

The United States, the second hardest hit country, said it had confirmed 160 cases in 21 states.

U.S. officials said they were encouraged by reports from Mexico that the outbreak may be leveling off, although they said it was too early to relax.

We are remaining vigilant, said Dr. Anne Schuchat of the CDC. We have seen times where things appear to be getting better and then get worse again ... I think in Mexico we may be holding our breath for some time.

Almost all infections outside Mexico have been mild. The only death in another country has been a Mexican toddler who was taken to the United States before he fell sick.

President Barack Obama said the United States was responding aggressively to the new flu strain.

He outlined steps being taken to address the virus, including school closures, and said antivirals were being distributed to states where they may be needed and new stockpiles had been ordered.

SEEKING ANSWERS

Scientists are still trying to assess how the new virus behaves and how it compares to regular seasonal flu strains, which kill between 250,000 and 500,000 globally every year.

Although the outbreak remains tiny compared to other epidemics such as malaria, hepatitis and meningitis, the WHO hiked its pandemic alert level from three to five last week due to its rapid spread and the possibility it could hit hard in poor and disease-prone communities, including among people with

HIV.

Ryan said the WHO would send more than 2 million treatment courses of antiviral drugs to poor countries to help them prepare for the virus, which is already causing havoc with a travel industry that flies hundreds of thousands of people to and from Mexico each week.

China suspended flights to Mexico after Hong Kong authorities on Friday confirmed a Mexican man who flew via the Chinese mainland was infected with the flu strain.

Police in surgical masks quarantined 200 guests and 100 staff inside a Hong Kong hotel where the Mexican, 25, had been staying, saying they would be confined for a week.

They said everybody needed to go back to their rooms. I don't want to go to my room because I want to be out, an Australian man at the hotel told a TV reporter by telephone.

Italy joined the list of European countries with confirmed cases of the virus.

Mexico has released a confusing batch of flu data in recent days but public hospitals have noted a steady drop in patients turning up with fevers, suggesting the infection rate may be declining as the nation dons face masks and uses hand gel.

Cordova said of 159 files on suspected flu deaths, tests showed 58 died of other causes. He said 16 deaths are confirmed as caused by the H1N1 flu and 85 are being tested.

In Mexico City, big parks, museums and zoos were shut and in the sprawling metropolis of 20 million people many were heeding a government call to stay home for a prolonged five day-holiday to try to stem new infections.

This is not a normal life. You can't walk around with gloves on all day and the kids won't wear those face masks, said resident Marisa Curria.

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